玄武湖混合流数值模拟研究

Study on numerical model for admixture flow in Xuanwu Lake

本文从二维浅水非恒定流的控制方程组出发,建立了玄武湖混合流水动力数值模式,应用伽辽金(Galerkin)有限元法对数学模型求解。对玄武湖出入流2m3/s流量及5.7m/s均匀定常东北风进行数值模拟验证基础上,研究了出入流2m3/s流量及6m/s均匀定常东风、西风、南风、北风、东南风、西北风六种风情组合作用下的玄武湖混合流特性。结果表明:玄武湖混合流流场受到吞吐流作用影响较弱,受到风作用影响较强,混合流流态表现为湖区若干环流和沿岸流的有机结合;沿岸流流向与风向一致,湖中较深的地方形成逆风流动的补偿流,流向与风向相反;玄武湖混合流场的形态由风向决定,不同方位风场作用形成的稳定混合流流态不同;对峙方向风场形成的混合流流型相似,流向相反。

Based on the two-dimension adlittoral non-invarialenes flow equations,a hydrodynamic model with open-boundary was built up in accordance with the feature of Xuanwu lake in this article. Applied the 2 D Galerkin finite element method mathematic model, this proposed model first simulated the current driven by 5.7m/s stead Northeast wind with 2m^3/s inflowoutflow in Xuanwu lake. The simulative results match the measured data very well, which shows the model and its solution method are suitable for modeling admixture flow in shallow lakes such as Xuanwu lake, Moreover simulated field of the admixture flow driven by the 6m/s stead East wind.West wind.South wind. North wind.Southeast wind. Northwest wind respective with 2m^3/s inflow-outflow. Analyzed and studied the morphological characteristic of admixture flow field under the conditions of the various wind regimes with 2m^3/s inflow-outflow. The conclusions drawn by modeling the flow field show as follows： the inflow -outflow have little effect on the admixture flow field except in the near region of the inlet opening, but the wind strongly influences all lake region. The shape of some circumfluence in the lake region combined with the current along the bank represents the state of the admixture flow of Xuanwu lake. The direction of coastwise current is accordance with the direction of wind, hut the direction of compensative current in deep lake sections is reverse with the direction of wind. The shapes and states of the admixture flow are chose by the wind directions. Different wind directions have different current states of the ad mixture flow. The state of the admixture flow driven by the wind of oppose directions is similar, hut the admixture flow directions are in reverse.